1. Field of the Invention
The present invention relates to cruise control apparatus for a hand grip throttle control and more particularly to a thumb actuated cruise control apparatus for releasably holding a rotatable hand grip throttle in a motorcycle at any given throttle position.
2. Description of the Prior Art
My hand grip throttles, particularly those used in motor cycles, are spring biased to return to idle speed condition when the operator's hand is released. To maintain a constant speed, the operator must hold the throttle firmly at the setting desired. In long distance motorcycle touring this can become very tiring. A cruise control device for fixing the position of the hand grip throttle is desirable for relieving hand muscle fatigue during extended constant motor speed. However, for safety purposes it is necessary that such devices include a means for immediate release of the throttle in the event of an emergency or otherwise where manual control is desired.
One type of cruise control device previously developed for a hand grip throttle involves the application of a continous frictional force to the hand grip, which in effect overcomes the spring bias return and holds the throttle in any given setting. Typically, the frictional force is applied by means of a resilient spring so as to limit the force applied and permit manual movement of the throttle while the frictional force is being applied. One problem with this type of device is that the friction is applied continuously even when the throttle is being released. This necessitates an increased force in an effort to change the throttle setting and it also poses a safety problem in emergency situations wherein an automatic spring return to an idle speed is desired. Another problem with this type of cruise control device is that because the frictional force applied is limited so as to permit manual movement of the throttle while the device is applied, the locking action is not positive and the throttle position can vary as a result of vibration or the application of a slight and unintentional rotational force.
Other types of cruise control devices have employed lugs, rollers, or projections mounted on the movable hand grip, which engage serrations, corregations, teeth or detents in a member mounted on the fixed portion of the hand grip or handlebar. One problem with certain of these devices is that they do not provide a completely continuous throttle adjustment. Rather, the throttle can be adjusted only to the position where the projection mates with the corregation or the like in the fixed member. Also, as in the continuous friction system described above, such devices are sometimes applied continuously and thus nullify the desirable attribute of a spring return throttle.